Left ventricular morphology influences mortality after the Norwood operation

Background: Within the spectrum of congenital heart disease referred to as hypoplastic left heart syndrome (HLHS), there is variation in the morphology and function of the left ventricle which could influence outcomes after stage I Norwood palliation. Objective: To determine if left ventricular (LV) morphology is associated with outcome after stage I Norwood palliation for HLHS. Methods: Echocardiograms were reviewed from 108 patients who had undergone Norwood palliation at our institution over the past 11 years. Total cardiac diameter, thickness of the interventricular septum (IVS), LV area and LV myocardial area were calculated. Competing risk analysis was performed for survival to a stage II operation and to determine potential predictors. Results: From the Norwood operation up to stage II operation, mortality was predicted by IVS thickness, while the absence of right ventricular (RV) dysfunction was predictive of survival to stage II operation. For the complete pathway, from Norwood to the Fontan operation, mortality was predicted by IVS, a lower RV fractional area change and the presence of significant tricuspid regurgitation. Cardiac transplantation during this period was predicted by a lower RV fractional area change (p=0.02) and a larger LV area in diastole. Conclusions: These results indicate that LV hypertrophy and decreased RV function adversely effect survival after the Norwood operation. They suggest that LV morphology, especially septal hypertrophy, can influence outcomes in HLHS and should be considered when evaluating treatment options.